Recommended classifications

Recommended classes in the Meteoritical Bulletin Database are assigned by the database editor.
In most cases, this is based on the most recent classification that appears in either the Catalogue of Meteorites, MetBase,
the US Antarctic Meteorite Newsletter, the Japanese Meteorite Newsletter, or the Meteoritical Bulletin. However, in a few
cases it reflects differences of opinion about the proper way to classify the meteorite. The
nomenclature used may also be modified by the editor to conform to an internally consistent classification scheme

The recommended classification CH3 means:

"A carbonaceous chondrite of the CH group of petrologic type 3."

The highlighted words are defined as follows:

carbonaceous chondrite: A major class of chondrites that mostly have Mg/Si ratios near the solar value and oxygen isotope compositions that plot below the terrestrial fractionation line.

CH group: The high-metal (CH) chemical group of carbonaceous chondrites, similar to Allan Hills 85085; CH chondrites have tiny chondrules and refractory inclusions (~0.02 mm), abundant metal (~20 vol%), no fine-grained matrix except as xenolithic clasts, and rare sulfides consistent with overall low volatile element contents. It is uncertain whether members of the group are true chondrites, as they may have formed slightly later in solar system history.

type 3: Designates chondrites that are characterized by abundant chondrules, low degrees of aqueous alteration, and unequilibrated mineral assemblages. Many of the low-Ca pyroxene grains are monoclinic and exhibit polysynthetic twinning. The type 3 chondrites may be divided into subtypes ranging from 3.00 (least metamorphosed) to 3.9 (nearly metamorphosed to type 4 levels). If primary igneous glass occurs in the chondrules, it belongs to type 3.